The present invention generally relates to drug delivery devices and containers, and more specifically relates to a syringe, as well as a tip cap assembly for securely sealing the tip of the barrel of the syringe.
Conventional syringes each include a barrel having an open proximal end and an opposed distal. A cylindrical wall extends between the ends and defines a substance retaining chamber. An elongate tip projects from the distal end of the syringe barrel and includes a narrow passage which communicates with the substance retaining chamber of the barrel. A plunger may be inserted into the open proximal end of the syringe barrel for sliding fluid-tight engagement with the cylindrical chamber wall. Sliding movement of the plunger in a distal direction urges fluid in the chamber through the passage in the tip. Conversely, sliding movement of the plunger in a proximal direction draws fluid through the passage in the tip and into the chamber of the syringe barrel.
Conventional syringe barrels typically are made of plastic or glass. Glass exhibits lower gas transmissivity than plastic. Thus, glass syringe barrels are used for medications that are particularly susceptible to interaction with ambient gases. Glass syringe barrels also are preferably used for medications that are pre-filled into the syringe barrel and stored for a considerable period of time prior to use.
Such syringes may further include a needle assembly with a needle cannula having a proximal end, a pointed distal end and a lumen extending axially therethrough. The needle assembly also includes a hub which is engageable with mounting means on the syringe barrel for selectively placing the lumen of the needle cannula in fluid communication with the passage through the tip of the syringe barrel. One prior mounting means includes a luer collar disposed in spaced concentric relationship around the tip of the syringe barrel. The luer collar includes an array of threads for threaded engagement with corresponding structure on the hub of the needle. For example, the luer collar may include an array of internal threads which are engageable with projections extending outwardly from the hub of the needle cannula. Syringe barrels formed from plastic may have the luer collar unitarily molded therewith. However, glass syringe barrels may not be easily formed with a unitary luer collar. Thus, glass syringe barrels and some plastic syringe barrels may have a separately formed luer collar securely mounted to the tip of the syringe barrel. The luer collar may rely upon a slip fit interengagement, a snap fit or other such secure mounting engagement around the tip of the syringe barrel.
Medications that are pre-filled into a syringe barrel must be sealed to prevent contamination or loss of the medication. Seals also prevent health care workers from being needlessly exposed to medications. The prior devices have included stoppers or closures mounted over the tip at the distal end of the syringe barrel to prevent leakage and to avoid contamination of the medication. Prior tip caps have been formed from elastomeric material frictionally and/or resiliently retained in engagement with the tip of the prior syringe barrel. The prior tip cap may be removed from the syringe tip shortly prior to usage of the syringe. The hub of the needle assembly may then be securely engaged with the luer collar or other mounting means adjacent the exposed tip of the syringe barrel. For example, the needle hub may be threadedly engaged within the luer collar such that the lumen of the prior needle cannula communicates with the exposed tip of the prior syringe barrel.
Prior elastomeric tip caps on the ends of pre-filled syringe barrels generally perform well. However, the resiliently and/or frictionally engaged type tip cap may be accidentally disengaged from the tip of the syringe barrel in response to inadvertent forces imposed thereon or due to dimensional changes or instability of the elastomeric seal. Additionally, the vacuum or suction effect created as the prior elastomeric tip cap is removed from the tip of the syringe barrel can lead to the loss of medication and unnecessary personal contact with medication that the tip cap is intended to avoid. Additionally, the prior elastomeric tip cap provides no evidence of tampering or misuse of a pre-filled syringe.
Thus, there has been a need for a syringe, as well as a tip cap, which would eliminate the problems and limitations associated with the prior syringes discussed above, most significant of the problems being evidence of tampering or misuse of a pre-filled syringe.
In contrast to the prior devices discussed above, it has been found that a syringe particularly suited for evidencing tampering or misuse of a pre-filled syringe can be constructed in accordance with the present invention. Specifically, the syringe of the present invention includes a tip cap which evidences tampering or misuse of the syringe.
The subject invention is directed to a syringe as well as an effective tip cap assembly for the syringe, and to a syringe assembly having a more effectively sealed tip. A syringe in accordance with the subject invention includes a barrel having a proximal end, a distal end and a chamber wall extending therebetween. The chamber wall defines a substance receiving chamber which may be pre-filled with a selected dose of medication in either dry or liquid form, as well as water or diluent used for reconstituting a medicament. The distal end of the syringe barrel includes a tip having a passage extending therethrough. The distal end may further include needle mounting means for selective engagement with mounting structure on a needle cannula. The mounting means may comprise a collar that is either unitarily formed with the syringe barrel or that is securely mounted to the syringe barrel in proximity to the tip. In addition, the collar may be a locking luer type fitting.
The tip cap of the subject invention includes an elastomeric material to form a soft inner cap frictionally and/or resiliently engageable with portions of the tip for sealing the passage through the tip. The tip cap assembly further includes a substantially rigid outer cap engageable with the needle mounting means of the syringe barrel and protectively enclosing the inner cap. The outer cap may be frictionally, resiliently and/or mechanically engaged with the inner cap. Thus, disengagement of the outer cap from the needle mounting means of the syringe barrel may simultaneously disengage the inner cap from the tip of the syringe barrel.
The inner cap and the outer cap may be separately manufactured and assembled to one another after manufacture. Alternatively, the inner cap and the outer cap may be integral with one another. In this regard, the inner or outer cap may define an insert in a mold cavity employing insert molding technology. Alternatively, the inner and outer caps may be formed by coinjection of appropriate materials into the mold cavity of an injection molding apparatus. Still further, the inner and outer caps may be formed respectively by sequential injection molding techniques using a single mold cavity.
The inner and outer caps may be assembled or molded together and subsequently attached to a needle mounting structure unitarily formed at the distal end of a plastic syringe barrel. Alternatively, the inner and outer caps may be assembled or formed together and then engaged with a plastic mounting collar for a glass syringe barrel. The assembled inner and outer caps and the mounting collar engaged therewith may then be securely mounted to the tip of a syringe barrel.
The subject invention may further include a tamper evident means connecting the outer cap to the mounting means. The tamper evident means may comprise a plurality of frangible portions separating the outer cap into a proximal portion and a distal portion.